How to do a neon light effect inside an object or be seen that way with blender 2.8?
You can use another texture to mix color with your emission texture map:

See the Checker texture &quot;Add&quot; to the emission socket, make it light up as the checker go white. That node is Color→MixRGB in node editor.
Photoshop is another approach if you only want a quick prototype and keep thing simple.